Trailer braking systems typically include a towing vehicle and towed vehicle. Application of the brakes of the towing vehicle generally occur through operator actuation of a brake pedal. It is usually desirable to apply the brakes of the towed vehicle in roughly the same proportion as the brakes of the towing vehicle are applied. Thus, the more forcefully the brakes of the towing vehicle are applied, the more forcefully those of the towed vehicle should be applied.
Where the brakes of the towed vehicle are electrically operated, the performance of the system may suffer from the lack of readily available electrical signal or data indicating the braking force applied by the brakes of the towing vehicle.
One type of system avoids the need for quantitative braking information by applying the towed vehicle brakes in a steadily increasing manner, up to a maximum value, each time the brakes of the towing vehicle are applied. However, this type of system requires proper calibration on the vehicle and skilled operation by the driver of the towing vehicle. Furthermore, the heavier the trailer, the more desirable it becomes to have the proportion of trailer application follow the proportion of towed vehicle brake application.
Other systems utilize one or more sensors which are used to measure the application force applied by the brakes of the towing vehicle. However, these types of systems are costly, due to the cost of the sensors, and require modification of the towing vehicle's safety critical braking system.
Another solution utilizes an accelerometer, such as a mercury switch, pendulum, or other acceleration sensitive mechanical device within the towing vehicle controller, to indirectly measure the brake application force by measuring or responding to the apparent deceleration of the towing vehicle.
One such system is disclosed U.S. Pat. No. 6,445,993 issued to. Larry Eccleston on Sep. 3, 2002. as indication of the braking of the towing vehicle. The Eccleston system uses an accelerometer mounted directly to a printed circuit board. The PC board is mounted in a device which is mounted within the cab of the towing vehicle. Mounting of the device is restricted to a prescribed range of angular positions. Not only does the device fail to function outside of that range, its operation degrades at a steadily increasing rate as its position departs from the center of that range, i.e., it becomes less and less sensitive to decelerations and more and more sensitive to bumps in the road.
The present invention is aimed at one or more of the problems set forth above.